Contributions of Nonhuman Animal Models to Understanding Human Speech Perception

Broadly speaking, there are two ways nonhuman animal models contribute to our understanding of speech perception by humans -- by analogy and by homology. The former, is the generally easier task and historical examples are more abundant. Because demonstrating strict homology requires deeper explication of underlying mechanisms, claims may be more precarious, but they carry greater explanatory potential. When studying the nonhuman organism as analogy, emphasis is most often upon how animal neurophysiological or behavioral processes have adapted to fulfill some requirement of a particular ecological niche. By contrast, study of nonhumans as homology must exceed the bounds of such niches in search of common underlying mechanisms across varying ecologies. In practice, this frequently involves undermining ecological integrity -- presenting non-ecological stimuli, intruding into the cranium, having subjects press bars or peck keys, and controlling experience in ways that are unethical with human subjects. When studying common underlying processes (homology), it also is true that nonhuman animals become a method more than an object of study. In service of revealing processes central to human speech perception, data from experiments with nonhuman subjects join a greater arsenal that also includes data from human perception studies and from computational simulations. The problem, not the organism, dictates these methods.